Question 28 – Elements, compounds and mixtures - Questions

The table shows some mixtures and methods of separation.

Identify the best method of separation for each mixture.

Separation	Chromatography	Simple distillation	Filtration	Fractional distillation
W: red pigment from a mixture of ink dyes
X: ethanol from a mixture of ethanol and water
Y: chalk from a mixture of chalk and water
Z: pure water from a sodium chloride solution

Which of the mixtures $W$ , $X$ , $Y$ or $Z$ contains an insoluble solid?

Pure dry crystals of potassium nitrate can be obtained from potassium nitrate solution by crystallisation.

The following steps describe the method, but they are in the wrong order:

F: filter the mixture to separate the crystals from the remaining solution
G: place the wet crystals in a warm drying oven to dry
H: heat the salt solution in an evaporating basin to concentrate it
I: allow the hot, saturated solution to cool slowly to room temperature
J: test for saturation by dipping a cold glass rod into the solution to see if crystals form

Show the correct sequence of steps by writing the letters in the empty boxes below. One letter has been filled in for you:

\boxed{\phantom{\text{H}}} \quad \boxed{\text{J}} \quad \boxed{\phantom{\text{H}}} \quad \boxed{\phantom{\text{H}}} \quad \boxed{\phantom{\text{H}}}